JEE Main & Advanced
Physics
Electrostatics & Capacitance
Question Bank
Electric Field and Potential
question_answer
Electric charges of \[+10\mu C,\ +5\mu C,\ -3\mu C\] and \[+8\mu C\] are placed at the corners of a square of side \[\sqrt{2}\]m. the potential at the centre of the square is [KCET (Engg./Med.) 1999]
A) 1.8 V
B) \[1.8\times {{10}^{6}}\] V
C) \[1.8\times {{10}^{5}}\]V
D) \[1.8\times {{10}^{4}}\]V
Correct Answer:
C
Solution :
Length of each side of square is so distance of it?s centre from each corner is \[\frac{\sqrt{2}}{\sqrt{2}}=1m.\] Potential at the centre \[V=9\times {{10}^{9}}\left[ \frac{10\,\times {{10}^{-6}}}{1}+\frac{5\times {{10}^{-6}}}{1}-\frac{3\times {{10}^{-6}}}{1}+\frac{8\times {{10}^{-6}}}{1} \right]\] \[=\text{ }1.8\times {{10}^{5}}V\]